As badminton shuttlecocks, there are those using waterfowl feather (natural feather shuttlecocks) and those using artificial feather (artificial feather shuttlecocks) artificially manufactured using nylon resin and the like, for the feathers.
As is well known, natural feather shuttlecocks have a structure using approximately 16 natural feathers of geese, ducks or the like, and the ends of the stems of the feathers are embedded into the hemispherical platform (base portion) made of cork covered with skin. And the feather used for natural feather shuttlecocks have a feature of the specific gravity being small and being extremely light. For example, the specific gravity of the stem portion is approximately 0.4 and the vane portion is approximately 0.15. Additionally, natural feather has high rigidity and thereby a unique flying performance and comfortable impression when hitting natural feather shuttlecocks can be perceived.
However, the feather used as the material for natural feather shuttlecocks are collected from the aforementioned natural waterfowls and moreover, feathers of specific portions of the waterfowl are suitable for shuttlecocks which does not mean that feathers from any portion of the waterfowl can be used and thus the amount of feather for a shuttlecock that can be collected from one waterfowl is a miniscule number. In other words, there is a limit to the amount of feather manufactured for use in natural feather shuttlecocks. Further, there has been a situation of a large amount of geese used for food that had been the main source for feather, being disposed due to bird flu epidemic in the recent years. Therefore, material procurement is predicted to become more difficult and the price of natural feather shuttlecocks to rise further in the future.
Meanwhile, shuttlecocks with resin feather integrally formed in a ring shape is well known as artificial feather shuttlecocks, however, the feathers of these artificial feather shuttlecocks do not move independently as with natural feather shuttlecocks so that flight performance similar to natural feather shuttlecocks is difficult to be achieved. For such reason, artificial feather shuttlecocks imitating feather has been proposed as described in the following PTL 1 through 3.
Here, when correspondence between portions of natural feather and portions of artificial feather based on ornithology is made, the portions corresponding to the vane and the rachis of natural feather will be called vane portion and the rachis portion, respectively, the portions corresponding to those called the basal and the calamus that protrude from the vane as a part of the rachis will be called the calamus portion to avoid confusion with feather. With such preconditions, the artificial feather described in PTL 1 has the vane portion and the rachis portion integrally formed with artificial material and the weight is reduced by making at least one of the vane portion the rachis portion hollow. Further, the artificial feather described in PTL 2 has a structure of the vane portion made from thin plated fiber dispersed resin sandwiched by two thin fiber-reinforced resin rods being the rachis portions while the basal portion of the rachis portions has a foam body inserted between the two thin rods. In the artificial feather described in PTL 3, a protruding portion is formed to protrude in the extending direction of the rachis portion at one end of the vane portion and the protruding portion is embedded in the rachis portion.